1. Field of the Invention
This invention relates to a tape recorder of the cassette type which includes a cassette guide post for positioning a tape cassette loaded in the tape recorder and a tape guide mounted for movement toward and away from the cassette guide.
2. Description of the Prior Art
Generally, in a tape recorder of the cassette type, a reel driving shaft, a cassette guide post and a capstan is located on a stationary main base plate of the tape recorder. Meanwhile, a tape reel, a positioning hole and a capstan hole are located or formed in a tape cassette to be loaded on a tape recorder. When a cassette is loaded in position on a tape recorder, the tape reel, positioning hole and capstan hole of the cassette are fitted respectively on the reel driving shaft, cassette guide post and capstan on the main base plate.
Further, the main base plate has a head carrying plate mounted thereon for movement toward and away from a cassette loaded in position on the tape recorder, and a recording/reproducing head, an erasing head and a tape guide are carried on the carrying plate. A pinch roller is also mounted on the main base plate and is moved into and out of contact with the capstan as the head carrying plate moves back and forth.
Thus, when the tape recorder is in a reproducing mode, the recording/reproducing head is contacted with a tape while the tape is held between the pinch roller and the capstan so that the tape is fed at a fixed speed by rotation of the capstan.
An arrangement of a tape guide and a guide post of an exemplary one of conventional tape recorders is illustratively shown in FIG. 3. Referring to FIG. 3, a cassette guide post 1 for receiving a tape cassette thereon is securely mounted on a stationary main base plate 2 and has a so-called tapering profile wherein a lower half has a cylindrical shape of a fixed diameter and a upper half has a substantially conical shape and is thus tapered toward an upper end thereof in order that a tape cassette may be smoothly received thereon.
A tape guide 3 is mounted in an opposing relationship to the cassette guide post 1 and for movement toward and away from the cassette guide post 1. In particular, the tape guide 3 is mounted on a head carrying plate 4 which is in turn mounted for movement toward and away from a tape cassette not shown loaded in position on the tape recorder. Accordingly, as the head carrying plate 4 moves toward and away from the cassette in position, the tape guide 3 is also moved toward and away from the cassette guide post 1.
The tape guide 3 has a tape contacting face 5 formed at an end thereof opposing to the tape cassette in position in a parallel relationship to a plane of a tape being fed in the tape cassette. The tape guide 3 further has a pair of widthwise movement limiting portions or guide portions 6a, 6b in the form of rounded projections formed at upper and lower ends of the tape contacting face 5 thereof for limiting lateral widthwise movement of a magnetic tape to be fed along the tape contacting face 5. Thus, if the head carrying plate 4 is moved to a tape reproducing position nearest to the cassette guide post 1, a magnetic tape T within a tape cassette loaded in position on the tape recorder is slidably contacted with the tape contacting face 5 of the tape guide 3. Then, during reproduction of the tape T, the lateral widthwise movement of the tape is limited or restranied by the upper and lower widthwise movement limiting portions 6a, 6b. Besides, the tape guide 3 has an additional function to stabilize, particularly where the tape recorder is of the automatic reversing type, vertical or lateral widthwise positions of the tape at left- and right-hand side positions with respect to a magnetic head not shown thereby to stabilize the crosstalk and separation between the tape and the head. In addition, the tape contacting face 5 of the tape guide 3 functions to provide a load to cause a back tension to act upon the tape due to a load caused by its sliding contact by the tape. Such a back tension acts to contact the tape closely with the tape contacting face of the head.
However, in the conventional tape recorder, the widthwise movement limiting portions 6a, 6b of the tape guide 3 have an equal extension from the tape contacting face 5. Besides, since the cassette guide post 1 and the tape guide 3 are located in an opposing relationship as described hereinabove, the extension of the widthwise movement limiting portions 6a, 6b from the tape contacting face 5 is relatively short so that the lower widthwise movement limiting portion 6b may not contact with the cassette guide post 1 when the head carrying plate 4 is in its tape reproducing position nearest to the cassette guide post 1. Accordingly, the conventional tape recorder has following problems.
In particular, when a temporary fast feeding operation (cuing operation) or a temporary rewinding operation (reviewing operation) is performed in the reproduction mode of the tape recorder, the head carrying plate 4 is retracted a little distance from its reproduction mode position, and the recording/reproducing head, tape guide 3 and pinch roller are moved away from the tape together with the head carrying plate 4. In this instance, if the retracting movement of the head carrying plate 4 proceeds slowly, then the tape will be fed at a high speed by rotation of a winding side reel driving shaft because the contacting pressure of the pinch roller reduces at a stage before the pinch roller is moved completely away from the capstan. Since the distribution of the contacting pressure of the pinch roller against the capstan over the axis of the capstan at this point of time is very unstable, the tape tends to move toward a location at which the pinch roller is contacted at a relatively high pressure with the capstan. Besides, since the tape guide 3 is at its retracted position at this point of time, the function of the tape guide 3 to prevent lateral widthwise movement of the tape does not operate sufficiently.
Consequently, the tape may move in a lateral widthwise direction. However, there will be no trouble if the tape moves toward the base end of the capstan. But on the contrary if the tape moves toward the free end of the capstan, there is the possibility that the tape may drop off the free end of the capstan and come around to the opposite side of the capstan remote from the pinch roller.
If this actually occurs, then the tape cannot be fed in a regular manner. Accordingly, the tape may be damaged or else twisted around itself.